A serious problem in burglar alarm systems is the possibility of false alarms. Whether the system sounds a local alarm or is in contact with a security force, such as the local police, there can be little tolerance to false alarms from any source. Such false alarms if possible can destroy the usefulness of a system by creating the classical condition of a boy crying "wolf". One time is too many. Yet little attention is given to resolution of this problem.
Systems that protect against opening or breaking windows or doors are also susceptible to false alarms because they depend upon closure of switch contacts to prevent an alarm. Thus, if a wood window frame shrinks during dry weather, switch contacts may become unaligned and trigger a false alarm. Most such switch contacts are exposed to an oxidizing atmosphere which tends to create an insulation film between two metal switch contacts, particularly after long periods of inactivity such as might occur in a switch protecting a window that is infrequently opened.
When occasional false alarms occur, it is very expensive to maintain and repair alarm systems to assure that they are working properly, because the cause of the false alarm is not easily determinable in many cases. Thus, it is desirable to have a system initially installed more reliably protected against possible false alarms.
It is therefore the object of this invention to provide a reliable burglar alarm system that is less likely to produce false alarms.